1. Field of Invention
The invention relates to a brake system for a vehicle, especially a small vehicle, such as an all-terrain vehicle or a utility vehicle, provided with a differential drive mechanism in a gear case in which a final reduction gear is housed.
2. Description of Related Art
Japanese Patent Laid-Open No. 59-130791/1984 discloses a conventional system as shown in FIG. 5, in which a gear case 101 is provided therein with a large final reduction gear 102, a differential drive mechanism 104 and a wet type multiplate friction brake 105 for braking a differential case 106 alone. The friction brake 105 is provided with a plurality of rotary friction plates 113 spline-fitted in a hub 112, which is fixed to the differential case 106, in such a manner that the rotary friction plates 113 can be axially moved, and a plurality of stationary friction plates 114 spline-fitted in an inner circumferential surface of the gear case 101 so that the stationary friction plates 114 can be axially moved.
There is another conventional system for arranging drum brakes, which are adapted to brake left and right axles independently, on the left and right sides of a gear case. In this system, levers of the respective brakes are combined together into a single operating mechanism, and both the left and right drum brakes are actuated by a single operation.
When a braking operation is carried out in the former conventional system while a vehicle travels straight, the skidding (revolution without load) of one side wheel does not occur since the differential drive mechanism is not operated. However, when a braking operation is carried out while the vehicle turns, the differential drive mechanism is operated to cause a floated wheel to skid (revolve without load) in some cases.
In the latter conventional system, in which drum brakes are arranged on the left and right sides of a gear case, two sets of brake parts, such as drums, shoes and levers, are required. Accordingly the number of parts increase, and a double brake installing space is required. Moreover, it is necessary to adjust the brakes so that balanced left and right braking forces are put forth.